fwiw, i went freestyle with math. We only did primary challenge so far, because challenge got to 2-variable algebra problems too quickly and scared my son. We did some time4learning early on, one singapore book, a bunch of murderous maths books, a few random 'fun' supplemental math books from scholastic teachers express, a few random printed practice worksheets off the web, LOF fractions and decimals/percents, a little khan academy, one class from here, and now we are reviewing using Spectrum Grade 6 workbook. Ok, his knowledge is very spotty and he's a tad lazy . . . but i plan to move on to LOF pre-algebra books. I'm not capable of staying on the straight and narrow path when he hates it. If we miss something, he can learn it quickly and easily when it comes up again (and if it never comes up, he didnt need it lol)